Automotive headlights, i.e. headlights for use on board of a vehicle, such as e.g. a car, motorcycle, truck or other type of vehicle generally comprise a reflector and, mounted therein, a lamp. Known incandescent lamps, in particular halogen lamps, generally comprise a base and a burner. The base provides mechanical and electrical connection to the automotive headlight, whereas the burner comprises the actual light-emitting element, in particular filament. Light emitted from the filament is reflected by the reflector to form a beam for illumination in front of the vehicle.
Different types of incandescent lamps are known, which comprise one or more filaments arranged within a vessel.
DE 10 2011 004 290 discloses a halogen incandescent lamp for automotive frontlights. Within a vessel, a filament is arranged which is dimensioned such that operation at an operating voltage of 13.2 V operation and at an electrical power of 22-27 W leads to a luminous flux of 400-600 Lumen (lm). The lamp comprises a single filament with 17-23 windings, a length of 2.1-3.6 mm and an outer diameter of the winding of 0.9-1.3 mm. The filament wire has a diameter of 95-105 μm. The interior of the vessel is filled with a filling gas of a halogen and a rare gas at a cold filling pressure of 0.7-1.5 Mpa.
US 2007/0008720 A1 relates to a lamp-reflector unit with a first and second light source axially disposed on the lamp axis. A low-voltage halogen incandescent lamp is fixed in the neck of a reflector with cement. A first filament has a rated power of 35 W and a second filament a rated power of 50 W. The first filament generates a narrow light beam and the second filament a wide light beam during lamp operation. If simultaneously operated, a circular symmetrical light beam of high luminous intensity is obtained.
WO 2008/055943 A2 describes a halogen bulb comprising two filaments located in a lamp body. The first filament is partially enclosed by a baffle and has a nominal voltage of 13.2 V or 28 V and electrical power of 55-80 W. In different embodiments, the first filament has 17.5 or 15.5 windings. The second filament has a nominal voltage of 13.2 V or 28 V and electrical power of 17-22 W. In different embodiments, the second filament has 27 or 28 windings.
Revision 4 of UNECE Regulation No. 37 of 26.10.2005 regulates automotive front lighting lamps of category HS1. These lamps are double-filament lamps with a low-beam filament shielded by a baffle and an unshielded high-beam filament and with the baffle partly extending in between the two filaments. The Regulation determines that the two filaments, being supplied with a test voltage of 13.2 V, ideally should operate each at an electrical power of 35 W and should emit a luminous flux of 525 lm for the low-beam and 825 lm for the high-beam filament.
It is an object to propose a lamp with a filament arrangement well suited for automotive front lighting application.